When to plant sunflowers in zone 5b
In zone 5b, where the last spring frost typically comes around May 1, sow outdoors May 1 to 22.
The zone 5b schedule for sunflowers
- Sow outdoors
- May 1 to 22
- Safest planting date (10% frost risk)
- May 16
- First harvest, roughly
- June 20 to August 20
From the median frost dates of the NOAA stations assigned to the 2,546 ZIP codes in zone 5b, and the timing recommended by Cooperative Extension guides for sunflowers.
Frost risk in zone 5b
Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 5b, the typical last frost ranges from about April 21 in the earliest tenth of ZIP codes to May 18 in the latest tenth, and the first fall frost from September 30 to October 19. For a typical place in the zone:
- April 18Risky: a later frost happens in 9 years out of 10
- May 1Typical: frost after this date in half of years
- May 16Safe: a later frost only 1 year in 10
Sunflowers are killed by frost, so if you want to be safe, plant out after the safe date rather than the typical one, or be ready to cover plants on a cold night.
Your dates for sunflowers
Set your ZIP code at the top of the page and we will work out when to plant sunflowers where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.
Sunflowers in zone 5b cities
| City | Typical last frost | Plant | Fall |
|---|---|---|---|
| Milwaukee, WI | Apr 19 | Apr 27 to May 18 | — |
| Madison, WI | May 1 | May 1 to 22 | — |
| Des Moines, IA | Apr 18 | Apr 18 to May 9 | — |
| Aurora, IL | Apr 19 | Apr 19 to May 10 | — |
| Fort Collins, CO | May 2 | May 2 to 23 | — |
| Naperville, IL | Apr 19 | Apr 19 to May 10 | — |
| Rockford, IL | Apr 24 | Apr 24 to May 15 | — |
| Elgin, IL | Apr 26 | Apr 26 to May 17 | — |
| Greeley, CO | May 2 | May 2 to 23 | — |
| Green Bay, WI | Apr 30 | Apr 30 to May 21 | — |
| Davenport, IA | Apr 19 | Apr 19 to May 10 | — |
| Longmont, CO | May 6 | May 6 to 27 | — |
How to grow sunflowersAll zonesSunflowers in zone 5aSunflowers in zone 6aAbout zone 5b
Sources
- Dakota Gardener: Grow a bouquet in 60 days · NDSU Extension (North Dakota State University)
- Growing Sunflowers in the Home Garden (Circular 1121) · University of Georgia Cooperative Extension
- Let's Grow Sunflowers · Clemson Cooperative Extension Home & Garden Information Center
- How to sow sunflowers in successful succession · Mississippi State University Extension
- How to Grow Sunflowers (Garden Notes GN 166) · UC ANR Cooperative Extension Sacramento County Master Gardeners
- Sunflowers · UF/IFAS Extension Gardening Solutions
- Flowers to Plant in Florida: Text (month-by-month calendar for North, Central and South Florida) · UF/IFAS Extension Gardening Solutions
- Flower Planting Guide for the Low Desert (AZ1100) · University of Arizona Cooperative Extension, Maricopa County
- Sowing Annual Seeds · Penn State Extension
- May 21, 2005 Timely Tips (Bexar County gardening calendar) · Texas A&M AgriLife Extension, Bexar County